Laser desorption ionization (LDI) based on laser-induced silicon microcolumn arrays was developed for mass spectrometry (MS) of biomolecules and other natural and synthetic products. The technique enables one to obtain intact molecular mass at low laser power and structural information (such as, e.g., peptide sequence) from in-source decay (ISD) and/or post-source decay (PSD) at high laser power. It can be used for small molecule analysis and peptide sequencing without using matrix molecules required for matrix-assisted laser desorption ionization (MALDI) or surface enhanced laser desorption ionization (SELDI).